Sodium soap thickened solvent extracted high viscosity index oil



Unite i Silo res Pate ice SODiUh/i SOAP THI JKENED SOLVENT EX- TRACTED HIGH VISCOEEITY INDEX OIL John M. Musselrnan, Breclrsville, and Cyril P. Nunley, Cleveland Heights, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application September 28, 1953 Serial No. 382,845

5 Claims. (Cl. 252-421) The present invention relates to a multi-purpose sodabase lubricating grease.

The grease lubricant art is one of the oldest arts known to mankind, dating back to about 1400 B. C. when greases were first used for lubricating chariot wheels. Probably, the first grease-like lubricants were animal tallow; but, when these proved unsatisfactory, further improvements were made necessary. A tremendous advance in the grease making art was made with the discovery of petroleum oil which resulted in the mineral oil greases similar to those known and used at the present time.

Ever since the inception of the first lubricating grease, grease making has been, to a large extent, an art in which the methods of cut and try have predominated. For this reason, the progress made in the manufacture of lubricating greases has been appallingly slow as compared with the development of other petroleum products. In fact, the grease making industry is still, in this present day, hampered by the lack of broad scientific knowledge which has resulted from the secrecy and mystery surrounding the activities of the skilled grease maker.

Today, practically all lubricating greases are prepared from mineral oil and a thickening or gelling agent. The oldest known thickening agents are the metallic soaps of fatty acids, such as the sodium and calcium soaps of relatively long chain fatty acids. Recently, however, other metallic soaps of fatty acids such as lithium, barium and aluminum soaps have achieved prominence as thickening agents for mineral oils. Also, in more recent years, various inorganic gelling or thickening agents have been proposed and used to some extent to replace the fatty acid soaps. Thus, we have today greases prepared from thickening agents such as silica aerogel, alumina, and various types of clays such as Attapulgus clay and bentonite.

Almost every thickening agent which has been used in the formation of a grease results in a grease which in one respect or another has superior properties. For example, the so-called soda-base greases, which are prepared from a sodium soap of a fatty acid, are known to have relatively good stability at reasonably elevated temperatures but such greases suffer the disadvantage of deteriorating rapidly in the presence of water, presumably due to the high solubility of the sodium soap in water. On the other hand, calcium soap greases are known to possess, in general, satisfactory resistance to Water for most purposes, but greases prepared from calcium soaps usually have such a low melting point that they are unsuitable for use in lubricating at higher temperatures. Lithium soap greases to a large extent bridge these properties and re looked upon with some favor in the art but, since lithium soaps are relatively expensive in comparison to sodium and calcium soaps, grease manufacturers would ordinarily prefer to employ one of the less expensive soaps. Similarly, excellent greases can be prepared from the inorganic gelling agents, hereinabove described, but again the high cost of such gelling agents is a prohibitive factor which limits the popularity of these greases.

From the preceding discussion, it is evident that the development of an inexpensive grease which does not possess the disadvantages normally attributable to calcium and sodium soap greases would be a decided boon to the art. The present invention fulfills the need for such a grease by providing a sodium soap grease which had excellent properties in the more important respects and which can be classed as a true multi-purpose grease. In order for a grease to be classified as a multi-purpose grease, it must possess several different physical properties, the attainment of all of which simultaneously in one grease represents an exceedingly difiicult achievement. One of the most important characteristics of a lubricating grease is the ability to withstand mechanical shear Without undue loss in consistency, and this property is referred to as mechanical stability. Consistency is measured in terms of the penetration of the grease at 77 F. using an ASTM conical type penetrometer. In measuring the ability to withstand working, the grease is mechanically worked in an ATSM greaseworker, which consists essentially of a piston and cylinder assembly wherein the piston is a flat disc having a multiplicity of rela tively small perforations. The cylinder is charged with the grease to be tested, and the piston reciprocated, thus rapidly forcing the grease back and forth through the perforations of the disc. In order to measure the mechanical stability of the grease, the penetration. is conventional'ly measured after working 0, 60, and 10,000 strokes. Ideally, the perfect grease would possess the same penetration at the beginning of the test as it possessed after being Worked for 10,000 strokes but, for practical purposes, a grease is considered to have excellent mechanical stability if the gain in penetration is less than about 30. The grease of our invention has this desirable property.

Another measurement of the mechanical stability of a grease is furnished by the Shell roll test which is considerably more severe than the ASTM test. in this test, the grease is packed inside a rotatable drum approximately four inches in diameter and ten inches long which contains a bar inside. Upon rotation of the drum, the grease is worked by movement of the bar and the penetration of the grease is measured before the test and at the end of the test by the Shell Microcone penetration test, Institute Spokesman (NLGI), vol. VI, No. 12, p. 1 (1943). The test is so severe that many greases Will liquefy during the test so that any grease which still retains its consistency at the conclusion of the test is considered to have excellent mechanical stability. The grease of our invention has excellent mechanical stability as will be seen from data hereinafter.

Another important property of a lubricating grease is its resistance to oxidation, and this is commonly referred to as oxidation stability. It has long been recognized that greases undergo certain chemical changes in storage and use. Oxidation takes place with the resultant formation of dark red or black polymers, malodor, changes in consistency, and, in certain cases, excessive oil separation. As a result, a large number of bearing manufacturers have incorporated in their specifications the requirement that the grease pass the Norma-Hoffman oxidation test. In this test, a 20 gram sample of the Patented Feb. 18, 1958 grease is'divided into five equal parts, each part isplaced in a Pyrex dish, and the dishes are placed on racks in a vertical, cylindrical stainless steel bomb which is very similar to the induction bomb used in gasoline testing. The bomb is then immersed in a 210 F. constant temperature oil bath during the test, and the material being tested is subjected to an initial oxygen pressure of .110 .p. s. i.' g. .(pounds per squire inch gauge). The loss in .pressure'with time is'then measured, and a loss of pounds pressure in less than 100 hours is regarded as equivalent to a satisfactory stability for at least two years.

Notwithstanding the'fact that'our grease, unless modified, has poor oxidation stability, the grease can be given adequate resistancetoioxidation by-the addition of a smallamount of anyof the conventional antioxidants, contrary to the result that imight have been expected from the use of antioxidants iii-greases ma'defromacidrefined oils.

Another important property of a :grease, which is often used as a criterion ofithegreases ability to-withstand elevated temperatures in service, is the melting point. The melting points of grease vary over a wide range. For example, the melting point of a calcium soap grease usually averages less than 200 F. while lithiuinand aluminuinsoap greases generally have meltingpoints in the range of 350 to 400 F. The-highest melting points are normally possessed by greases prepared=from-the-inorganic gelling agents, such as bentonite, aerogels, and Attapulgus clay, and which often have melting points in excess of 400 F. Sodium soap greases, in general, normally have melting points in excess of 300 F. with the better sodium soap greases having melting points in the range of about 375 to 390 F. in summary, it can be said-that any grease which possesses 'a melting point in excess of 400 F. has the desirable characteristic of-being able to withstand relatively high temperatures during service. Our grease'meets this requirement.

The water resistance of a grease is another very important characteristic since in many types of application a greasemust perform its function in thepresence of water whether from rain or other sources. Heretofore, calcium soap greases have been considered generally superior from the standpoint'of water resistance whereas sodium soap greases have been considered notoriously poor in this respect. The first test devised by the industry for the measurement of the water resistance of a grease consisted of shaking five grams of a grease in water, and then allowing themixture to stand while noting the timerequired for the grease todeteriorate. For the purposes of the present invention, this test is designated as the water immersion test. To be satisfactory in this test, a grease of grade No. lz-should have a deterioration time of atleast one year. This test is met by thegrease of the invention.

.Another test which determines the waterresistance of a grease is called the A81 M water washout test. In this test, .aball bearing is packed with the grease and a stream of water at 100 F. is played on the race of the hearing from 0.25 inch above the angular openingfor one hour. The results are reported in the percent of .greaseretained-in the bearing. In this test a rating of 60% or .better is excellent. Notwithstanding the fact that our grease is a soda-base grease, which class of grease in-the past has had a poor reputation on this score, our grease has satisfactory water resistance.

There is still another very important property of a grease, which heretofore has not received the full consideration that it merits, and which is termed the dispensability of the grease. This is the property which enables a grease to be dispensed easily from the cans, drums or other containers in which it is normally sold. It is especially important because of the fact that a *grease is --nor1na1ly removed from such. a container by means of a pump-like attachment which withdraws the grease by vacuum.

There are two sub-characteristics which determine the dispensability of a grease. The first of these is pumpability which is self-explanatory. The second subcharacteristic is known as slumpability and of the two sub-characteristics the latter is much more diflicult to achieve. The slumpability of a grease refers to the ability of a grease to levelout in a container instead of adhering to the .sides of a container when part of the grease is removed from the central Zone of the container. The importance of this characteristic known as slump- .ability is apparent when one realizes that the intake tube of a pump attached to a grease container usually terminates in the center of the container near the bottom. If the grease inthe container does not possess slumpability, the pump will cease to-operate long before the container is empty because the grease fails to flow downward toward the intake end of the tube. The importance of dispensability is readily apparent if one visualizes the frustration of .afarmer trying-to pump grease out of a drum on a cold winter morning in order to get his tractor greased and started.

Themeasurement of slumpability is performed in an apparatus known as an EZ Grezeratorwhich is a piston and cylinder arrangement adapted to fit into a conventional grease container. .Slumpability is measured by the amount of grease sucked into the cylinder under 21 inches of vacuum at l0 F.,in a period of 15 seconds. If the grease does not possess slumpability, the intake of the cylinder willnotbe-continually immersedin the grease and the amount of the grease sucked into the tube will be small. In this test, a ratingof -is a perfect score'anda rating of zero is the poorest score obtainable. Our grease is'excellent in this important requirement.

Another important characteristic of a grease is its tex ture. Thisproperty is especially'important because it afiectsthe appearance-of-the grease and, consequently, its salability and also-affects theease of application of the grease. The desirabilityof a grease having a smooth and butter-like texture as contrasted to a fibrous, stringy texture for many purposes is well known. Lime greases usually have this buttery texture and the soda greases of our invention possess it in contrast to their usual fibrous texture.

it is also desirable-in many cases that. a grease have the property'of not affecting articles of rubberwith which it comes incontact. For example, rubber seals are often employed retaining elements for'grease and a grease which will act upon rubber and result in its deterioration is obviously unacceptable. It is an advantage of the greaseof. this invention. that it does not affect such rubber seals.

It is a primaryobjectofthe present invention'to provide a multi-purpose grease which, in comparison with other greases grade for grade, is excellent in all of the properties hereinabove discussed and which, in addition, is inexpensive-because it utilizes a relatively cheap sodium soap as a thickening agent.

Throughout the long history of grease-making, much experimentation,involving a wide variety of oils and of soaps, has beenperformed in the manufacture of sodium soap greases. in this experimentation, it has continually been found that both the'oil component and the soap component contribute to the final properties of the grease and that the selection of both of these components must be made with care.

Most of the experimentation with sodium soapgreases had involved the use of an acid-refined oil, largely be cause acid refining has been an inexpensive and the most widely used method of refining. Numerous fatty acid soaps have been suggested as thickening agents for the acid-refinedwil's 'includingsQaps of practically every acid frornC 'up. .lto C andhi'gher both saturated and unsaturated. However, .ithas; never been possible to prep'are from aniacid-refinedoil, a. soda-base grease having a water resistance which even approaches the water resistance of calcium and lithium soap. greases. On the other hand; it has been possible to prepare. greases which have acce'ptable mechanical, stability by employing as thickening agents sodium soaps of fatty acids which have a relativelyhigh amount of unsaturation.

. .Heietofoi'e, solvent-extracted oils have been used as components .efsodium soap lubricating greases only for certain specialty purposes. Therefore, every little is known concerning the properties of greases prepared from.isolvent-ext1'acted oils and it has generally been ihOllghtxthiilkthE solvent-extracted oils were the approxiniategequivalfent of the acid-refined oils in grease-making. One of the reasons why the art has generally avoided the use}ofsolvent-extractedoils ingrease-making is that the solvent-extracted oils requirelarger amounts of soap to thicken them and the incorporationof larger than usual amounts of soap inthe oil. is .diflicult.

5,1116, previous manufacturing.experiences with acid-refined oilsthave furnished no guide or ruleof predictability which can l e-followed in the manufacture .of greases fromsolyent-extracted oils. Invariably, greases prepared from acid-refined oils and a sodium soap of a fatty acid have notoriously poor resistance to water no matter what typeof acjdtis used in..the formulation. In fact, such reases .deteriorateso rapidly in water that the only known methods for evaluating waterresistance can give no measurable results. From knowledge such as this, it will ordinarily be predicted that greases prepared from solvent=extracted em and sodium soaps of fatty acids would alsobe notoriously poor in water resistance. We have found that this is not so when a grease is prepared from a solvent-extracted oil and the components are carefully selected. t I a i As another instance of unpredictability it is known that, while soda-basegreases prepared :from acid-refined oils can be made with fairly good mechanical stability, optimum mechanical stability can be obtained only by the use, as. a thickening agent, of a sodium soap of a relatively unsaturated acid and that, as a generalrule, the greater, the degree of unsaturation, the greater ,is the mechanical stability of the resultant grease. Proof of this statement has been furnished by preparing several greases from acid-refined oils each thickened with 20% by weight of a sodium soap of a fatty acid having a chain length of C 3 with varying degrees of unsaturation from grease to grease. The procedure later to be described, in Example 1 was employed and the mechanical stability of the greases was determined by the ASTM method. The data are presented in the following table:

TABLE I Penetration Gain (10,000 strokes) Iodine Value of Fatty Acid ;,In order to formulate the grease of the present invention is prepared should be substantially saturated. The

effect obtained by varying the degree of .unsaturation of the fatty acid used in the preparation of the grease of the invention has been shown by formulating a series of greases according to the procedure of Example 1 but usingwc acids ofvarying degrees of unsaturation, and then determining the mechanical stability of the greases by the ASTM test. The data are as follows:

TABLE II Penetratio'ii Iodine Value of Fatty Acid Gain (10,000

strokes) This data, when compared with the data in Table I, illus-- tratcs one of the differences between acid-refined oils and.

solvent-extracted oils in grease formulations. v

.In accordance with the present invention, it has been: found that the grease of the invention which has all of the valuable properties hereinabove contributed to it must be prepared from the sodium soap of a fatty acid, i. e.,. an aliphatic hydrocarbon acid, which has the following characteristics: The acid must have an iodine value of less than 5, preferably less than 3; it must be composed of at least by weight of C or higher acids, preferably at, least by weight; it must contain less than 20% by weight, preferably less than. 15% by weight of C acids; and it must also contain less than 2% by weight, preferably less than 1% by weight of C and lower acids. There is no critical limit on the maximum chain. lengthof the fattyacid and good results can be obtainedwith acids as high as C C or even higher. The latter figure represents a practical upper limit on the chaimlength.

While the above specifications may appear to encompass a large numberof acids, actually only a very few acids are included since most of the acids sold commercially, are mixtures, of acids which do not meet the specifications. ,For. example, the commonly used fish oil acids are too highin C and C content and too high in unsaturation. Menhaden oil, for instance, contains about 32% of C acids and 5% of C acids. Herring oil contains about 7% C acids and 27% of C acids and sardine oil contains about 4.5% of C acids and 23% of C acids. Even when hydrogenated, the: fish oil acids still contain percentages of C and C acids too great to be acceptable. All available grades of commercial stearic acid, which by its narnewould appear to meet the characteristics, contains not more than 50% of C or higher saturated acids. In fact, there is no naturally occurring oil or fat whose fatty acid content meets the above specifications. In order to meet the specifications, it is necessary to subject a naturally occurring fat or oil through several steps of processing. For example, a fatty acid which meets the specifications can be prepared by hydrogenating fish oil acids to reduce the iodine value to the designated level and then fractionating out the lower acids so. that the C and C content is reduced to an extent sufficient to meet our specifications.

. The solvent-extracted oil which is combined with the sodium soap of the fatty acid of the type hereinabove defined to provide the lubricating grease of the invention need not be selected with theparticularity required aaaeoee for the fatty acid. However, the oil must meet certain specifications in order to be acceptable. It must have a viscosity index of at least 85, preferably at least 95; an aniline point of at least 100 C., preferably at least 115 C.; a viscosity within the range of 100 to 2,000 SSU at 100 F; and a pour point of F. or below. If desired, a pour point depressant may be used to attain the desired low pour point. The use of viscosity index improvers to meet the viscosity index specification is permissible but generally not practicable. This is be cause oils of low viscosity index generally also possess a low aniline point and, while a V. I. improver is capable of improving viscosity index, it will not raise the aniline point to meet our specification. In order for the oil component to be satisfactory, both the aniline point and viscosity index specifications must be met.

The preparation of the grease preferably involves the in situ formation of the fatty acid soap in the oil. A typical preparation comprises weighing the solvent-extracted oil and a calculated amount of sodium hydroxide into a. mixing vessel and then heating these materials to an elevated temperature, generally in excess of 150 F.,. and a calculated amount of fatty acid is then weighed into the mixer. The mixer is again started and heating is.

continued at a temperature of approximately 300 F- After heating at the elevated temperature for about 10 to minutes, until saponification is complete, an additional quantity of solvent-extracted oil is added to the mixer and heating is continued until a total processing time of about 2% to 3 hours has elapsed. Heating is then discontinued and during the cooling of the crude grease mixure, an additional calculated quantity of solvent-extracted oil is added with the final oil addition being made at a temperature in the neighborhood of 225 to 230 F- Cooiing is then continued until the grease is at a tem-- perature suitable for packaging.

As mentioned above, the grease of the present inven* tion requires a greater proportion of fatty acid soap than a similar grease prepared with an acid-refined oil. However, the amount of fatty acid soap is not critical and,

the amount of soap may be varied to provide grease of difierent grades, all of which, however, possess the excellent characteristics attributable to the present invention when compared with other greases of the same grade.

It is explained at this point that greases are conventionally made in several different grades according to hardness. The various grades are designated by number and range from grade No. 000 for a very soft grease up to grade No. 6 for a very hard grease. Usually, the

principal ditference in formulation between different a grades of the same grease is that the softer greases contain less thickening agent than the harder greases. This means that generally the softer grades of grease will have different consistency than the harder grades of grease and, therefore, when one wishes to compare two or more greases of different formulation, each grease should be of the same grade. In the preparation of the grease of this invention, it has been found that a grade No. 000 grease requires about 3 to 5% of soap; a grade No. 0 grease requires about 11 to 14% by weight of soap; a grade No. 1 grease requires about 16 to 17% by weight of soap; a grade No. 2 grease requires about 24 to 25% by weight of soap; and a grade No. 6 grease requires upwards of soap. From this information it can be said that the grease of the present invention preferably contains from about 3 to about by weight of the fatty acid soap. The different grades of grease made by varying the soap content of the oil all possess the excellent properties attributable to the grease of the invention since variations in soap content affect only the consistency of the grease.

Gther ingredients can be present in the grease by virtue of their incorporaion during the preparation of the grease. it is especially desirable to incorporate a conventional amount, i. e., about 0.5, to 2% by weight of any con- 'ventional oil antioxidant such as Calco MB (tetramethyl diamino diphenyl methane), Ortholeum 300, or dimethyl para-cresol. This is so because the grease of the present :invention is unusually susceptible to the afiect of an antioxidant and the addition of an antioxidant results in a .an antioxidant may be omitted without detracting from 'the other properties of the grease.

The fact that the grease of the present invention is unusually susceptible to the affect of an antioxidant is another result which would not have been predictable :from previous experiences using acid-refined oils in grease manufacture. It is quite well known, for example, that the improvement resulting from the addition of an antioxidant to a grease prepared from an acid-refined oil is not enough to justify the use of an antioxidant. On the other hand, the grease of the present invention when prepared without an antioxidant has relatively poor OXIdEItlODi stability, but the addition of an antioxidant increases the oxidation stability to a remarkable extent that the grease of the invention can be prepared, if dGSllBd, with an oxidation stability comparable to the :majority of better greases on the market.

The invention will now be illustrated by specific examples in which parts and percentages are by Weight unless etherwise specified.

Example 1 An oil blend was prepared by mixing together equal a parts of a solvent-extracted bright stock oil having a visfound to possess the following characteristics:

Pour point 10 F. Viscosity at 100 F 841.7 SSU. Viscosity at 210 F 81 SSU. Viscosity index 96.3. Aniline point 260 F.

Six pounds of the oil blend and 2.8 pounds of 4850 Baurn sodium hydroxide were weighed into a mixer. These materials were heated with agitation at 180 F. and the mixer was then stopped. There was then added 9 pounds of fatty acid (Hydrofol acids) having the following characteristics:

iodine No 3.0 maximum. Titer 62 to 64 C. Acid No 195-201. Saponification No 196-202.

The acid was composed of about 90% stearic acid and 10% palmitic acid.

The mixer was again started and heating continued to about 295 to 300 F. The temperature was held at about 300 F. for 10 to 15 minutes and after a total processing of about 60 minutes, 10.5 pounds more oil and 0.35 pound Calco MB were weighed into the mixed m1xer over a period of about 20 to 30 minutes causing a drop of about 20 F. in the temperature. Heating was continued until a temperature of about 295 to 300 F. was again reached, controlling the temperature rise so as to reach the desired temperature after about minutes total processing time. At this point, heating was stopped and cooling started, along with the addition of 10.5 pounds of additional oil blend. When the mixture had cooled to 225 to 230 F., the final oil addition (6.5 pounds) was made, with the addition of oil bein completed before the mixture was below 210 Agitation I 9 and cooling were continued until the grease was at a temperature of 160 F. The mixer was then stopped and the grease withdrawn. 1

The grease of this lexamplehad a soap content of approximately 23%. It possessed an initial ipenetration I at 77 F. of about 290.,and after, 10,000 strokes working in the ASTM greaseworker, the penetration rose tqonly 300, a gain of about 10. The melting point of the grease was in excess of 400 F. and in the Norma-Hoffman oxidation test, there was a pressure loss of only about one pound after 100 hours. In addition, the grease possessed excellent water resistance. (a deterioration time of more than one year by the water immersion test) and good dispensability. it also possessed an excellent texture being smooth and buttery as contrasted to. a fibrous, stringy texture. It also rated excellent in the EZ Grezerator test.

A repetition of the example in which the antioxidant was omittedresulted in a grease which had a pressure loss of 100 pounds in the Norma Hofiman oxidation test. This shows the value of an antioxidant inour gr'ease.

Example A A grease was prepared according to the exact procedure of Example 1 with one exception. A saturated fatty acid having an average chain length two carbon atoms less than the acids employed in Example 1 was .used. The resultant grease possessed much poorer, water resistance 3 to 4 months by the water immersion test) than the grease of Example l and thus the grease is not classifiable as a multi-purpose grease.

Example 1-B A grease was prepared according to the exaetprocedure of Example 1 with one exception. A fatty acidhaving the same average chain length as the Hydrofol 15 acids but having an iodine value of about 50 was substi Example I-C A grease was prepared according to the exact procedure of Example 1 with one exception. A blend of acid-refined oils which possessed approximately the same viscosity. and pour point as the blend of solvent-extracted oils employed in Example 1 was substituted for the latter. The resultant grease was decidedly. poorer than the grease of Example 1 particularly in regard; to water resistance and mechanical stability. In the water-immersion test almost immediate deterioration was noted and in the ASTM greaseworker test, a penetration gain. of about 110 was noted after l0,"000strokes; These facts show that this grease fails as a trfierriulti purpose grease.

The results of Examples l-A 1.-B and l-C. illustrate the sensitivity of the grease of the invention (Example 1) to changes in formulation which result in a grease outside the scope of the invention. Example 1-.A sh0wls that fatty acids of shorter chainlength. than that specified are not suitable because the resultant grease possesses very poor water resistance. Example 143 shows that the use of a fatty acid' of high iodine value seriously detracts from the mechanical stability and water resistance of the grease and Example 1-C demonstrates the relatively poor qualities of a grease prepared from an acid-refined oil and the soap used in the present invention.

Example 2 A grease was prepared according to the procedure of Example. 1 with one exception. There was substituted for the Hydrofol 150 acids used in Example l an equal A-grease was prepared according to the procedure of Example 1 with the followingexceptions: A solventextracted bright stock oilhaving a viscosity of 750 SSU at F. was substituted for the oil blend used in Example 1. The bright stock oilhad an aniline point of about 246 lF. -a pour point of 0? R, and a viscosity index of 95. Also the, amount of fatty acid and (@ustic was increased so that the finished grease had a soap content of 27%. The result was a grade No. 2 grease of excellent characteristigs. V The penetration gain after 10,000 strokes working in the ASTM greaseworker was only 1. In the ASTM water washout test 74% of the grease was retained. The melting point was over 400 F.

Example 4 1 A grease was prepared according to the procedure of Example 1 withthefollowing exceptions: For the oil blend used in Examplel there was substituted a blend ofithree oils, including the solvent-extracted bright stock oil used in Example13 in the amount of 51.3% of the finished. grease, a solvent-extracted.neutral oil having a viscosity .of SSU at 100 R, an aniline point of 220 F. and .& pour point of 0 F. in. the amount of 17.3%; of. the. finished grease, and a solvent-extracted neutral oil having a viscosity 013.330 SSU at 100 F., a pour point of 0" R, and an aniline point of 230 F. in the amount of 17.3%.of the finished grease, the viscosity index of the blend exceeding 95. The amounts of fatty acid and caustic were reduced to provide a finished grease. having a-soap content of about-13.6%.. The result wasa grade No. 0 grease of excellent char-- acterist-ics. It possessed a ratingof 60.5% in the ASTM water washout test and in the ASTM greaseworker test it showed a penetration gain of only.4 after 5,000 strokes.

Themelting point of the grease exceeded 400 F. The

grease possessed a slumpability rating of 113 which isv excellent.

Example 5 p, grease was preparedaccording to the procedure- Example 5-A The grease of Example 5 was compared extensively with a number of competitive greases prepared not only from sodium fatty acid soaps but also from other metal soaps and from inorganic gelling agents. The tests upon:

which'the comparisons were based include melting point;

mechanical stability, including both the ASTM grease worker test and the Shell roll test; water resistance by the ASTM water washout test; and slumpability as measuied bythe EZ Grezerator. The results ofthese comparative tests are presented in the following table which also includes a description of the various greases. All greases except thatof Example 4 and the last grease in the table are greases prepared and sold commercially at the present time and are representative of the best prod-- ucts produced by leading oil companies in this country...

The result was- TABLE III ASTM Grease- Shell Roll Test, ASTM Grease Description worker Test, Penetration Water Thickening Melting Penetration Washout Slumpability,

Agent Point, Test, E-Z

F. Percent Grezerator Source Oil Component Initial After 10,000 Initial After Grease Strokes Working Retained Example 4 Solvent-Refined 01'1, Sodium soap 400+ 356 354 (5,000 197 235 09. 3 10%-Good.

770 SSU at 100 F., saturated C strokes). 94 V. I. acids, 16.4% Gain= Commercial Grease #1 Acid-Refined oil, 400 Sodium soap, 350 338 357 (5,000 180 liquid... 43.4 55-Average.

SSU at 100 F., 70 14%. strokes). V. I. Gain=19 Commercial Grease #2 2,000 $8111 at 100 F., Calcium soap, 190 30g IiI1 40 348 250 do 57.9 47-Fair.

70 a Commercial Grease #3 500 SSU tit 100 F., Caltiium soap, 190 33%} 28 360 178 193 46. 34 0Poor.

52.1 V. ain= Commercial Grease #4 257 SSU at 100 F., 71 Lithg m soap, 350-400 30lm 49 356 170 221 57. 4 Do.

V. 9.1 a Commercial Grease #5 53%SSU at 100 F., 35 Lithilim soap, 350-400 |in 72 328 120 205 54.6 5Ioor.

. I. 10. a Commercial Grease #0 1,247 SSU at 100 F., Alumirium 190-220 312 I 356 171 291 43. 24 6Ioor.

59 V. I. soap, 5.6%. Gain=44 Commercial Grease #7 471 SSU at 100 F., 48 Barium soar... 350 310G l 64 364 170 liquid... 27. 4 -Ioor.

I. ain= Commercial Grease #8 1,374 S811I at 100 F., Bentone 400+ 32?} im 13 341 157 191 66. 49 iii-Average.

11.6 a Experimental Grease #9 Solvent-Extracted oil, Attapulgus 400+ 325 I 321 186 175 35.0 126-Excel- 800 VSSIU at 100 F., Clay. Gain=0 lent. 94

From a study of the table, the outstanding all-around characteristics of the grease of the invention are apparent. For example, it is to be noted that the competitive sodium soap grease is markedly deficient in water resistance; the lithium soap greases are poor in dispensability and mechanical stability; the calcium soap greases are exceptionally low melting; the aluminum grease has poor water resistance and dispensability; the barium soap grease is poor in many properties; only the greases prepared from a bentonite clay and Attapulgus clay even approach the properties of the grease of the invention.

From the foregoing description of the invention, it can be seen that by selecting a particular solvent-extracted oil and by even more particularly selecting a particular type of fatty acid from the vast number of oils and fatty acids which have been suggested as components of lubricating greases, the present invention provides an inexpensive grease of exceptionally good characteristics which renders it useful for many varied purposes. Thus, the invention is seen to reside in a combination of particular ingredients which is believed to'be novel.

Many modifications Within the scope of the invention may be made by those skilled in the art. For example, it is possible to incorporate in the grease any of the known additives or fillers in order to produce a superior grease for a special purpose. The term consisting essentially of as used in the appended claims does not exclude the presence of substances such as these which do not alter the basic and novel characteristics of our grease. 7

it is obvious that many such changes and modifications in various details of the invention can be made without departing from the spirit thereof. Accordingly, the invention is to be limited only by the scope of the appended claims.

We claim:

1. A multi-purpose lubricating grease consisting essentially of from about 60 to about 97% by weight of a solvent-extracted mineral oil having a viscosity of about 100 to 2000 S. S. U. at 100 F, a pour point at least as low as about 10 F., a viscosity index of at least 85, and an aniline point of at least 100 C., said oil being thickened with the sodium soap of a fatty acid in the amount of about 3 to about by weight of the grease, the fatty acid being composed of at least 80% by weight of C and higher acids, less than 20% by weight of C acids and less than 2% by weight of C and lower acids, the amount of unsaturated acids being sufiiciently low to provide an iodine value of less than 5. 5

2. A multi-purpose lubricating grease consisting essentially of from about 60 to about 97% by Weight of a solvent-extracted mineral oil having a viscosity of about 100 to 2000 S. S. U. at 100 F., a pour point at least as low as 10 F., a viscosity index of at least 95, and an aniline point of at least 115 C., said oil being thickened with the sodium soap of a fatty acid in the amount of about 3 to about 40% by weight of the grease, the fatty acid being composed of at least by weight of C and higher acids, less than 15% by weight of C acids and less than 1% by weight of C and lower acids, the amount of unsaturated acids being sufliciently low to provide an iodine value of less than 3.

3. A lubricating grease according to claim 1 which contains a minor percentage of an oil antioxidant to improve the oxidation stability of the grease.

4. A grease according to claim 1 in which the fatty acid is composed of about stearic acid and about 10% palmitic acid, and in which there is incorporated an amount of tetramethyl diamino diphenyl methane to improve the oxidation stability of the grease.

5. A grease according to claim 1 in which the fatty acid is composed of about 38-39% arachidic acid, 29-30% behenic acid, 17-18% stearic acid, 1314% palmitic acid, and traces of unsaturated acids and in which there is incorporated tetramethyl diamino diphenyl methane in an amount to improve the oxidation stability of the grease.

References Cited in the file of this patent UNITED STATES PATENTS 1,989,196 Hilliker Jan. 29, 1935 2,229,367 Brunstrum et a1 Ian. 21, 1941 2,318,847 Flint et a1. May 11, 1943 2,428,123 Morgan et al. Sept. 30, 1947 2,534,053 OHalloran Dec. 12, 1950 2,588,280 OHalloran Mar. 4,1952 2,595,556 Worth et a1 May 6, 1952 2,598,154 Bailey et al May 27, 1952 2,626,896 Dilworth et a1. Ian. 27, 1953 2,626,898 Dilworth et al Ian. 27, 1953 OTHER REFERENCES Manufacture and Application of Lubricating Greases, Boner, Reinhold Pub. Co., N. Y. (1954), pp. 157-8.

Chemical Refining of Petroleum, Kalichevsky and Stagner, R inhold Pub. (30., 2nd ed. 1942 p. 72. 

1. A MULTI-PURPOSE LUBRICATING GREASE CONSISTING ESSENTIALLY OF FROM ABOUT 60 TO ABOUT 97% BY WEIGHT OF A SOLVENT-EXTRACTED MINERAL OIL HAVING A VISCOSITY OF ABOUT 100 VENT-EXTRACTED MINERAL OIL HAVING A VISCOSITY OF ABOUT 100 AS ABOUT 10*F., A VISCOSITY INDEX OF AT LEAST 85, AND AN ANILINE POINT OF AT LEAST 100*C., SAID OIL BEING THICKENED WITH THE SODIUM SOAP OF A FATTY ACID IN THE AMOUNT OF ABOUT 3 TO ABOUT 40% BY WEIGHT OF THE GREASE, THE FATTY ACID BEING COMPOSED OF AT LEAST 80% BY WEIGHT OF C18 AND HIGHER ACIDS, LESS THAN 20% BY WEIGHT OF C16 ACIDS AND LESS THAN 2% BY WEIGHT OF C14 AND LOWER ACIDS, THE AMOUNT OF UNSATURATED ACIDS BEING SUFFICIENTLY LOW TO PROVIDE AN IODINE VALUE OF LESS THAN
 5. 